As known, in calipers for disc brakes, the pads are pressed by at least one piston against the braking band of the associable brake disc. In the braking release step, the piston stops exerting the thrust action; however, the pad that is in contact with the braking band tends to remain in position, generating a residual braking torque and an annoying noise and a perceived vibration at the wheel.
For this reason, it is known to provide the calipers with plates or springs which exert a thrust action on the pads away from the brake disc. Obviously, during the braking step, such a thrust action is overcome by the braking action exerted by the pistons, but in the release step, said plates exert a thrust sufficient to move the pads away from the brake disc, avoiding contact between the pads and the brake disc when no braking action is required.
However, prior art solutions have several drawbacks.
In fact, the thrust exerted by the prior art plates is not in axis with the axial guides of the pads themselves; in fact, the pads are guided axially, i.e. parallel to the rotation axis of the associable brake disc, by pins or guides which slide in appropriate holes made in the support plates of the pads themselves. A friction is exerted between the pins and the related holes which, together with the axial thrust exerted by plates, generates a torque on the pad itself.
Such a torque tends to rotate the pad with negative effects both in terms of retraction and in terms of wear of the pad itself.
In fact, the rotation of the pad tends to make it jam on the guide and prevents a complete retraction sufficient to eliminate all the residual torque. Furthermore, the pad portion which remains in contact with the brake disc tends to wear and thus generate an abnormal wear of the braking surface of the pad.
Moreover, this abnormal wear also affects the braking efficiency and can cause the onset of vibration and noise during the braking itself.